The present invention relates to a process for laying synthetic underground piping, according to which a ground channel is first bored and the piping introduced thereinto, as well as apparatus for carrying this process into effect.
There are various boring procedures, so-called horizontal boring procedures, already known for producing ground channels for subterranean laying of piping, wherein primarily bore flushing and a course-controlled bore head are employed which permit boring of corresponding ground channels along a piping course predetermined by a plan, with adequate accuracy of direction. These processes have thoroughly proven themselves, since they enable the laying of supply and sanitation piping in underground procedures with a minimum of necessary excavation work. The actual laying of the pipes is achieved by drawing a run of piping, made up of lengths of pipe, during the drawing procedure into the ground channel, which proves relatively expensive and time-consuming and requires large handling pits and surfaces. Furthermore, the annular gap between the external pipe length surface and the internal ground channel surface must be selected large enough depending on connection technology of the individual pipe lengths and the preset laying lengths with the associated friction forces, by means of which the ground channel diameter is to be up to twice as great as the external diameter of the run of piping. This again means additional load with respect to excavation and discharge of material, ground flush quantities and propping of ground channels, as well as logistical dumping-related requirements and the like. In addition, the connection impacts of the pipe lengths always signify an increased risk of corrosion and fault point.
The object of the invention is therefore to indicate a process of the type described at the outset which permits efficient laying of underground piping, extensively disconnects fault points created by connection impact and also assists in minimising and variably shaping handling pits and surfaces, avoiding pipe insertion paths, reducing necessary transport and warehousing services and minimising as far as possible the demand for special dump sites for the discharged material and bore flushing, as well as required quantities of support fluid and the like. Also, an effective apparatus for carrying the process into effect is to be created.
The present invention solves this task by the piping, comprising a hardening synthetic mass, being manufactured at the same time as it is being introduced into the ground channel, in that the prepared synthetic mass is continuously formed inside the ground channel as a run of piping and left to harden. Accordingly, the run of piping is formed directly in the ground channel itself, resulting in a continuous pipe free of pipe lengths and without any insertion procedure necessary. For this purpose, the synthetic mass, which can be hardened by age by use of, for example, synthetic resin by mixing the individual constituents such as epoxy vinyl ester resin, reinforcement agent, MEK peroxide as catalyst and cobalt octoate as well as dimethyl aniline as activator, required for manufacturing the pipe only needs to be prepared and then pressed or formed and left to harden into the run of piping inside the ground channel. The tanks provided for holding the constituents can be erected at any suitable site, from where the constituents are conveyed by way of flexible pressure hoses without difficulty to the respective processing site, such that expense and space requirements are minimal. The run of piping being produced continuously inside the ground channel does not contribute any fault points caused by impact and the diameter of the ground channel must be only slightly greater than the external diameter of the run of piping.
It is effective if the synthetic mass inside the ground channel is prepared by intermixing of individual separately supplied constituents, such that there is no danger of premature incipient hardening of the synthetic mass and additional space requirement for external preparation plants is also avoided.
In order to be able to carry out this laying process efficiently, a reactor which can be drawn through the ground channel, comprising a front reactor drum and a rear double-sheathed calibrating cylinder is provided, whereby reactor drum and calibrating cylinder are arranged coaxially to one another and relatively rotatably and lines for supply of constituents terminate in the reactor chamber of the reactor drum and the reactor chamber is connected by way of a nozzle ring to the calibrating space, open from below and formed from the double mantle of the calibrating cylinder. For laying the piping the reactor is drawn through the pre-fabricated ground channel, for which purpose apparatus from horizontal boring technology, such as drill strings and back reamer and the like, is employed. As the reactor is being drawn through, the constituents for preparing the synthetic mass are introduced into the reactor chamber of the front reactor drum by means of appropriate supply lines, where they are mixed into a hardenable synthetic mass which then penetrates into the calibrating space of the calibrating cylinder by way of the nozzle ring. Here in the calibrating space the synthetic mass is formed continuously into the run of piping which is extruded out behind the calibrating cylinder while the reactor is being drawn through the ground channel and hardens into the piping inside the ground channel. By means of the relative torsional capacity of the reactor drum relative to the calibrating cylinder, the calibrating cylinder itself remains torsional inside the ground channel, despite rotation of the reactor drum, such that there is no twisting of the run of piping.
To improve preparation of the synthetic mass and to achieve thorough mixing of the supplied synthetic constituents, the reactor drum, which rotates as the reactor is being drawn through the ground channel, exhibits mixing tools projecting into the reactor chamber.
If the reactor drum exhibits guide runners projecting radially outwards or a guide ring, when the reactor is being drawn through the ground channel, this creates a centering guide for the reactor drum and the attached calibrating cylinder, so that the drawn out run of piping is laid by forming of the most uniform possible annular gap opposite the ground channel wall in the ground channel itself, whereby the annular gap can be filled with flushing or support liquid.
According to another embodiment of the invention an end piece which can be joined detachably to the calibrating cylinder belongs to the reactor. This end piece sealing off the calibrating space and exhibiting a ventilation device can be anchored torsionally in the inlet vicinity of the ground channel. The end piece facilitates initial forming of the run of piping, since it initially seals off the calibrating space and can be anchored torsionally at the ground channel inlet as the reactor is being inserted into the ground channel and at the correct height. The synthetic mass can now be prepared by impacting the reactor chamber with the synthetic constituents and pressed by raising the admission pressure in the calibrating space until the appearance of the synthetic mass from the ventilation device signals that the calibrating space is completely filled with synthetic mass. The connection between the end piece and the reactor can now be broken and the reactor drawn through the ground channel, whereby the run of piping, which has its beginning stuck in the end piece and remains torsionally anchored by way of the end piece, is extruded continuously, securely preventing the run of piping from twisting. Also, the height of the run of piping or of the pipe length required according to project can be adjusted geodetically precisely by means of the position of the end piece.
In order to be able to influence the forming of the run of piping or the hardening process the double mantle of the calibrating cylinder can be heated, by which the synthetic mass extruded into the run of piping by way of the double mantle can be heat-treated. In the process, the double mantle can be provided inside and/or outside and along the entire length or only in part sections with suitable heating devices.
It is important here that any heat transfer from the calibrating cylinder to the reactor drum is prevented by corresponding insulation measures.